The present invention relates to a computer aided designing and drafting system or drawing co-ordinates input device used in CAD.
Japan Patent Publication No. 62-59329 discloses a co-ordinates input device of a type of integrated digitizer and display device composed by overlapping a position detection tablet or a digitizer on the display device in order to display patterns or shapes on the display device. The applicant of this application has developed another input device for CAD provided with a digitizer and a display device integrated for displaying right angle scale lines with graduation in the display device, and drafting a drawing on the display device on the basis of these right angle scale lines. It is well known that an input device used for CAD indicating an enlarged area of drawing lines on the display device and enlarging the area to enlarge it.
As shown in FIG. 19(A) depicting a conventional input device for CAD in which while graduated right angle scale lines are displayed on the screen of the display device, patterns are drawn on the screen, an enlarge indication area 98 is set in the screen 96, the pattern 100 shown in the screen 96 is enlarged together with the right angle scale lines 64 and they are displayed on the screen as shown in FIG. 19(B). It is noted that because the pattern is simply enlarged in scale, the pattern 100 and the right angle scale lines 64 in the enlarged area 102 are enlarged in their length and width of these lines. Consequently, when you want to draft fine drawing or treat the pattern finely on the enlarged screen 104, such operation and treatment is disadvantageously difficult due to large width of lines shown in the display.